How do you convert apk to .aia?

i have apk on my desktop,( delveloped by some other developer) on start new project on app inventor says files are required to be .aia.... can some one guide how to convert so i can run on MIT App Inventor and do changes any required , humble requests.

You cannot, I repeat cannot, convert an apk to an aia.

You will need to find the aia project, or create a new project in AI2 and build it from scratch.